I looked at them when I upgraded my battery. Reviews were mixed across the 4x4 community. I ended up going with a XP from Batteries Plus 27F size. I think it was around $30 more than the Optima. They have a 5 year replacement vs. 3 for the Optima. I don't think they stock them at many stores so they take a few days to get in. I think they have a $30 rebate right now and if you order online and pickup in store they give you 10% off
I currently have one. That being said the 35 series red top I had stopped holding a charge two months before the warranty expired. I played their game with "testing" it. The month the warranty expired I tested my alternator out put running and then stored voltage and when it got really bad I went back in and they hooked their tester up and they verified it was the battery not holding the charge. So I paid like $50.00 upgrade difference in price and that is how I ended up with my 27f.
All that a side it definitely handles winch pulls better than the smaller 35 series red top I had previously.
